1. Field of the Invention
The invention relates to the manufacture of small diameter needle wire for use in the manufacture of medical instruments, for example, endoscopic suturing apparatuses. In particular, the invention relates to a method and apparatus for creating notches in small diameter steel alloy needle wire for use in the manufacture of endoscopic suturing apparatuses.
2. Description of the Prior Art
The recent development of continuous endoscopic suturing devices, such as those disclosed in commonly owned U.S. patent application Ser. No. 11/394,163, entitled “SURGICAL SUTURING APPARATUS WITH COLLAPSIBLE CHAMBER”, which is incorporated herein by reference, has necessitated the development of curved needles. As those skilled in the art will certainly appreciate, these needles continuously move through a loop as they pass sutures in and out of tissue. In order to ensure the needles do in fact continuously loop through a circular path, it is necessary that the needles be manufactured to very high tolerances.
The needles used in these suturing apparatuses are commonly produced of small diameter steel alloy needle wire. Some suturing apparatuses require that notches be cut along the needle wire. As those skilled in the art will certainly appreciate, the formation of appropriate notches at the ends of small diameter needle wire and the curvature of the small diameter needle wire, for example, wire having a diameter of less than 0.100″, is very difficult. In fact, notch production for utilization in conjunction with medical instruments requires that the needle wire cannot be deformed in any way by the notching process, the mechanical properties of the basic wire materials cannot be altered by the notching process and/or the metallurgical properties of the wire cannot be altered by the notching process. Similarly, usage in the manufacture of suturing apparatuses requires that the curvature of the needles can not vary or the needles will not function properly when placed within the suturing apparatus and required to rotate in a continuous loop of a predefined diameter.
All of these difficulties are compounded by the small diameter of the needle wire. The small diameter is necessitated by the small diameter loops through which the needles must pass when used in accordance with the designs of endoscopic suturing devices. In particular, designers of these suturing devices are continuously striving to reduce the profile of the suturing devices. One limiting factor in the reduction of the profile of these endoscopic suturing devices is the diameter of the loop through which the needle must rotate in the application of a suture. The smaller the potential diameter, the smaller the profile of the suturing device may be (that is, so long as the remaining components are designed to work in conjunction with the reduced diameter path of the suturing needle).
With the foregoing in mind, it is very difficult to consistently and effectively form notches in small diameter needle wire for suturing needles used in the production of endoscopic suturing devices. A need, therefore, exists for a method and apparatus which provides a convenient, reliable and cost effective manner for producing notches in small diameter steel alloy needle wires. The present invention provides such a method and apparatus.